Seal with Retaining Profile

ABSTRACT

A valve seat for a ball valve. The valve seat having a valve seat body with a circumferential concave seating surface configured to mate with a curvature of the valve ball. A seal pocket formed within the valve seat body, the seal pocket having (i) an throat formed in the concave seating surface, (ii) an outer pocket sidewall, and (iii) an inner pocket sidewall. A retaining groove positioned below the throat on either the outer pocket sidewall or the inner pocket sidewall and a flexible seal element shaped for positioning in the seal pocket. The seal element includes (i) an extended lip configured to rest within the retaining groove when the seal element is seated in the seal pocket, and (ii) a sealing face with an upper end laying below the valve seat&#39;s concave seating surface and a mid-portion extending upward above a curvature path of the concave seating surface.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 USC § 119(e) of U.S.Provisional Application No. 62/596,296 filed Dec. 8, 2017, which isincorporated by reference in its entirety.

BACKGROUND OF INVENTION

The invention relates to seals used in valves generally and inparticular embodiments, seals used in ball valves. Prior art ball valvestypically have a valve ball positioned between two valve seats withO-ring type seals interfacing between the valve seats and the valveball. FIG. 1A shows a cross-section of a cartridge type ball valve suchas seen in U.S. Pat. No. 9,488,033, which is incorporated by referenceherein in its entirety. The cartridge valve 75 includes upper and lowervalve seat carriers 76 and 77. The valve seat carriers hold the upperand lower valve seats 78 and 79. The valve ball 81 is positioned betweenthe valve seats 78 and 79. O-rings 80 are position in grooves on thesurface of the valve seats facing the valve ball and provide a sealbetween the valve seats and valve ball. The stem 84 is rotated in orderto rotate valve ball 80 and thereby open and close the ball valve.Although not shown in FIG. 1A, the above elements will typically beinserted into a tubular cartridge housing. As is clear from FIG. 1B, thevalve seat carriers and valve seats are annular in shape forming acentral valve passage 86, which is opened and closed when the ballpassage 87 is aligned and misaligned with the valve central passage 86.The central axis 88 (also referred to as the “central longitudinalaxis”) of the valve extends through and parallel with central passage86.

The conventional O-rings between the valve seats and valve ball oftenexhibit certain drawbacks in use. For example, the pressurized fluidsbeing controlled by the valve may sometimes force the O-ring from itsgroove in the valve seat. Similarly, the valve ball moving from its opento closed position (or vis-a-versa) can have a tendency to drag theO-ring from its groove, e.g., when the edge of passage 87 catches on theO-ring. A sealing system overcoming these drawbacks would be asignificant improvement in the art.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A illustrates a cross-section of a prior art cartridge type ballvalve.

FIG. 1B illustrates an exploded view of the FIG. 1A ball valve.

FIG. 2 illustrates a partial cross-section of one embodiment of thevalve seat the present invention.

FIG. 3A illustrates an enlarged section of the valve seat of FIG. 2 withthe seal element removed.

FIG. 3B illustrates an enlarged section of the seal element.

FIG. 4 illustrates the valve seat with the seal element partial insertedinto a seal pocket.

FIG. 5 illustrates the seal element fully inserted into the seal pocket.

FIGS. 6A and 6B illustrate reverse perspective views of one embodimentof the seal element.

FIG. 7 illustrates a first alternative embodiment of the valve seat.

FIG. 8 illustrate a second alternative embodiment of the valve seat.

FIG. 9A illustrates a third alternative embodiment of the valve seat.

FIG. 9B illustrates a detailed section of the FIG. 9A embodiment.

FIG. 10 illustrates a fourth alternative embodiment of the valve seat.

FIG. 11 illustrates the comparative width of the seal pocket throat andthe seating surface.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

FIG. 2 is a partial cross-section illustrating one embodiment of thevalve seat 1 and the overall valve of the present invention. FIG. 2suggests how the valve seat 1 includes the seal element 40 and ispositioned in valve seat carrier 62. The valve ball 60 will engage valveseat 1 (a “lower” valve seat as shown in FIG. 2) and seal element 40 andbe rotated by valve stem 64. Although not shown in FIG. 2, it will beunderstood that a similar “upper” valve seat 1 and valve seat carrier 62will engage the opposing surface of valve ball 60 much as seen in FIG.1A. It will also be understood that the valve seat has an annular ortoroidal shape as seen in FIG. 1B. The other elements of the overallvalve, including the valve seat stop 50, are similar to thecorresponding elements seen in U.S. Pat. No. 9,488,033.

FIG. 3A illustrates in more detail the valve seat 1 and the seal element40 (removed from valve seat 1 in FIG. 3A). Valve seat 1 will generallyinclude seat body 3 having the seal pocket 15 formed therein. The sealgroove 9 will accommodate a conventional seal to create sealing contactwith the inner surface of valve seat carrier 62. The surface of seatbody 3 facing the valve ball (i.e., the upper surface of the lower valveseat) will include a concave seating surface 4 having a curvaturecorresponding to (i.e., configured to seal against) the convex surfaceof the valve ball 60. The seating surface 4 is divided by seating pocket15 into an inner seating surface 4 b and outer seating surface 4 a.Seating surface 4 b is the “inner” surface in the sense that it iscloser in the radial direction to the center of the annular valve seat,while seating surface 4 a is the “outer” surface as it is more distantfrom the valve seat center. In the illustrated embodiment, the width ofthe inner seating surface 4 b is wider, for example by at least 50%,than outer seating surface 4 a. In the FIG. 3A embodiment, the sealpocket 15 is formed with a throat 16 which extends downward from thelevel of the concave seating surface 4. Seal pocket 15 further includesthe outer sidewall 17, the shorter inner sidewall 19, and the bottomwall 18. However, inner sidewall 19 need not be shorter in allembodiments. Again, the “inner” and “outer” terms designate positionsrelative to the center of the valve seat. In the FIG. 3A embodiment, theouter sidewall 17 and inner sidewall 19 extend generally parallel to thedirection of the central axis 88 (see FIG. 1B) of the overall valve.FIG. 3A further shows the concave retaining groove 25 formed in theouter sidewall 17 at a point just below outer seating surface 4 a. Inthe nonlimiting example of FIG. 3A embodiment, outer sidewall 17 has aheight of between about 0.09 and about 0.32 inches, while inner sidewall19 has a height of between about 0.06 and about 0.19 inches. In certainembodiments, the length of the inner and outer sidewalls are at least50% the width of throat 16. The dashed line 20 in FIG. 3A illustratesthe imaginary curvature path if the concave seating surface 4 wascontinuous between outer seating surface 4 a and inner seating surface 4b.

FIG. 3A also illustrates the seal element 40 prior to its being insertedinto seal pocket 15. This embodiment of seal element 40 has a body 41generally shaped to mirror the dimensions of seal pocket 15. Thisincludes the outer face 46, the inner face 45, and the sealing face 42.The general ring-like shape of this embodiment of seal member 40 can beseen in FIGS. 6A and 6B. In the illustrated embodiment (as seen in FIG.3B), sealing surface 42 has a generally convex curvature with a radiusof curvature R₁ ranging from between about 0.050 and about 1.2 inches,and more preferably, between about 0.1 and about 0.6 inches. Theextended lip 44 transitions from the upper end 43 of sealing face 42,extending radially outward beyond the outer face 46, before curving backinto outer face 46. In many embodiments, the flat inner face 45 of theseal element 40 is sufficiently long that it engages the inner pocketsidewall 19 prior to the extended lip 44 moving below the valve seat'sseating surface 4 a. As one example of a valve seat with an ID of 6.5inches, the seal member could have a bottom width of 0.25 inches, anouter face height of 0.303 inches, and an inner face height of 0.17inches.

In certain embodiments, the radius of curvature R₂ of the extended lip44 will be between about 0.01 and about 0.1 inches. Likewise, thematerial from which seal element 40 is constructed should besufficiently flexible to allow extended lip 44 to bend past seatingsurface 4 a, but rigid enough that the seal member may be pressed intoseal pocket 15. An example of seal material rigidity could be betweenabout 40 and about 80 (or any sub-range there between) on a Shore Ahardness scale. In a preferred embodiment, the seal member 40 isconstructed of glass filled or impregnated Teflon, such as FLON 700 25%glass filled PTFE available from Flontech USA, LLC of Pittston, Pa., butcould be of any conventional or future developed material having thecharacteristics required to perform its sealing function. In oneexample, seal member 40 has sufficient rigidity to hold ball member 40off the seating surface 4 at pressures (i.e., pressure on the opposingsurface of the ball) under 350 psi, but then deflects sufficiently toall ball member 40 to engage the seating surface 4 at pressures over2,000 psi.

FIG. 4 suggests how the lower portion of seal element 40 is insertedinto seal pocket 15. FIG. 4 shows seal element 40 partially insertedinto seal pocket 15 with the extended lip 44 not yet engaged withretaining groove 25. FIG. 5 shows seal element 40 completely insertedinto seal pocket 15. It can be seen that extended lip 44 rests inretaining groove 25. Additionally, the upper end 43 of seal element 40rests below the edge of outer seating surface 4 a. The mid-portion ofsealing face 42 extends above the curvature path 20 of seating surface4. In many embodiments, this mid-portion of the sealing face will extendbetween about 0.020 and about 0.075 inches above the curvature path ofthe seating surface.

FIG. 7 illustrates a modified embodiment where retaining groove 25 ispositioned midway down outer pocket sidewall 17. The extended lip 44 onseal element 40 has been positioned at a corresponding location down theouter face 46. As described above, the lower portion of seal element 40(h₅ in FIG. 7) should be sufficiently long that, when inserting sealelement 40 into seal pocket 15, inner face 45 of the seal element 40 atleast begins to move into seal pocket 15 (i.e., engaging inner sidewall19) before extended lip 44 encounters outer seating surface 4 a. Avariation of this embodiment is seen in FIG. 10. In the FIG. 10 example,the bottom wall 18 of seal pocket 15 is not perpendicular to innersidewall 19, but rather forms the angle β with such perpendicular line.Bottom wall 18 inclines from outer sidewall 17 to inner sidewall 19 in a“downward” direction, i.e., in a direction away from throat 16 of sealpocket 15. It can be seen how, upon insertion of the seal element 40,the lower edge of seal inner face 45 engages inner sidewall 19 prior tothe lip or groove on the seal moving against outer seating surface 4 a.

In still further embodiments not illustrated, retaining groove 25 couldbe positioned on the inner pocket sidewall 19. Likewise, as suggested inFIG. 8, other embodiments could reverse the concavity and convexity ofseal groove 25 and extended lip 44. For example, FIG. 8 shows anextended lip 30 could be formed on outer wall 17 and a groove 50 on sealmember 40. The seal lip (whether convex or concave) is considered tohave a “mating surface” with the opposing portion of the seal pocket(whether concave or convex).

FIGS. 9A and 9B illustrate a still further embodiment of the invention.This version of valve seat 1 includes a single outer circumference sealgroove 9 (as opposed two seal grooves in the previous embodiments). Aswith the previous embodiments, the valve seat of FIG. 9A includes a seatbody 2 having a concave annular outer seating surface 4 a and innerseating surface 4 b, separated by the seal pocket 15. This embodiment ofseal pocket 15 likewise includes an outer sidewall 17, a bottom wall 18,and an inner sidewall 19. One difference with the FIG. 9A embodiment isin the shape of the retaining groove 25. As most clearly seen in FIG.9B, the rear face 27 of retaining groove 25 forms a substantiallyvertical, straight line extending from a lower edge 6 of the outerseating surface 4 a. As used in the context of FIGS. 9A and 9B,“vertical” means parallel to central axis 88 of the valve (and thusvalve seat) as seen in FIG. 1B, while “substantially” typically meanswithin +/−20° from vertical. FIG. 9B illustrates how the rear face 27extends radially outward beyond the outer sidewall 17 by a distance W₂.In preferred embodiments, W₂ is between 0.020 inches and 0.040 inchesand the rear face 27 has height h₃ of between 0.030 inches and 0.090inches. In these embodiments, the rear face of the retaining grooveforms a right angle with respect to an undercut of the lower edge of theouter seating surface (i.e., the orientation of the distance W₂ is atsubstantially right angles with the height h₃).

FIG. 9A also shows how retaining groove 25 further includes thetransition section 26 which slopes inward and downward from theretaining groove rear face 27 to the retaining groove outer wall 17. Inthis embodiment, the slope of transition section 26 is between 20° and70° (or any subrange in between) relative to the line of outer wall 17.In certain preferred embodiments, the rear face 27 of the retaininggroove 25 will have a height slightly greater than (e.g., at least 0.000to 0.003 inches greater than) the corresponding height of the extendedlip 44 of the seal element 40. It will be understood that forming theheight of the extended lip 44 somewhat less than the height of rear face27 allows seal element 40 to more reliably be fully inserted into sealpocket 15 without placing the seal material in undue compression, whichcould urge seal element 40 to become dislodged from seal pocket 15.

FIG. 11 illustrates how the throats of the above described seal pockets15 provide a greater sealing area than the corresponding throats ofconventional o-ring seal pockets 115. FIG. 11 shows the seal pocket 115formed for a conventional o-ring. The throat width of seal pocket 115approximates the o-ring diameter and is represented by the distance W₅.The width of the seating surface 4 is represented by the distance W₃.For conventional o-ring seal pockets, W₅ is typically less than 40% ofW₃. The throat width of seal pocket 15 is represented by the distanceW₄. In many embodiments described herein, the throat width of the sealpockets 15 will be at least about 45% of W₃ and less than about 80% ofW₃.

The invention also includes methods of manufacturing the above describedvalve seats. These methods include providing a ball valve seat having aconcave seating surface and a central longitudinal axis. Then a sealpocket is formed in the concave seating surface with the seal pockethaving the shape and dimensions as described herein. In certainembodiments, the valve seat already has a seal pocket for a conventionalo-ring and this seal pocket is re-shaped into the substantialrectangular seal pocket having a wider throat as seen in the Figures.

Although many aspects of the invention have been described in terms ofcertain specific embodiments illustrated above, many modifications andvariations will be obvious to those skilled in the art to which theinvention pertains. All such modifications and variations are intendedto come within the scope of the following claims. The term “about” asused herein will typically mean a numerical value which is approximateand whose small variation would not significantly affect the practice ofthe disclosed embodiments. Where a numerical limitation is used, unlessindicated otherwise by the context, “about” means the numerical valuecan vary by +/−5%, +/−10%, or in certain embodiments+/−15%, or possiblyas much as +/−20%. Similarly, the term “substantially” will typicallymean at least 85% to 99% of the characteristic modified by the term. Forexample, “substantially all” will mean at least 85%, at least 90%, or atleast 95%, etc.

1-39. (canceled)
 40. A valve comprising two valve seats with a valveball positioned between the valve seats, at least one of the valve seatscomprising: (a) a valve seat body with (i) a central passage and acentral axis extending along the central passage, and (ii) acircumferential concave seating surface configured to mate with acurvature of the valve ball; (b) a seal pocket formed within the valveseat body, the seal pocket having (i) an throat formed in the concaveseating surface, (ii) an outer pocket sidewall, and (iii) an innerpocket sidewall, the outer and inner pocket sidewalls being orientedsubstantially parallel with the central axis: (c) a retaining groovebelow the throat on either the outer pocket sidewall or the inner pocketsidewall; (d) a flexible seal element shaped for positioning in the sealpocket, the seal element including (i) an extended lip configured torest within the retaining groove when the seal element is seated in theseal pocket, (ii) a sealing face with an upper end laying below thevalve seat's concave seating surface and a mid-portion extending upwardabove a curvature path of the concave seating surface, and (iii) a flatinner face of the seal element sufficiently long that the inner faceengages the inner pocket sidewall prior to the extended lip moving belowthe valve seat's seating surface; and (e) wherein a width of the throatis at least 45% of a width of the seating surface.
 41. The valveaccording to claim 40, wherein the seal element's sealing surface isconvex.
 42. The valve according to claim 41, wherein the retaininggroove is positioned along an upper end of the outer pocket wall. 43.The valve according to claim 41, wherein the seal element includes (i) aflat outer face with the extended lip formed at the top of the outerface, (ii) a flat inner face shorter than the outer face, and (iii) thesealing surface transitioning from the outer face to the inner face. 44.The valve according to claim 40, wherein the inner seating surface is atleast 50% wider than the outer seating surface.
 45. The valve accordingto claim 40, wherein the seal member holds the ball member off theseating surface at pressures under 350 psi, but deflects sufficiently toall the ball member to engage the seating surface at pressures over 2000psi.
 46. The valve according to claim 40, wherein the sealing face has acurvature allowing an outer end of the sealing face and an inner end ofthe sealing face to rest under the seating surface, while a mid-portionof the sealing face extends at least 0.020 inches above the curvaturepath of the seating surface.
 47. The valve according to claim 46,wherein the retaining groove includes a substantially vertical, straightline rear face extending from a lower edge of the outer seating surface.48. The valve according to claim 47, wherein a transition section of theretaining groove slopes inward and downward from the retaining grooverear face to the retaining groove outer wall.
 49. The valve according toclaim 47, wherein the rear face of the retaining groove extends radiallyoutward beyond the outer sidewall at least 0.020 inches.
 50. The valveaccording to claim 47, wherein the rear face of the retaining groove hasa height of at least 0.001 inches greater than a corresponding height ofthe extended lip of the seal element.
 51. The valve according to claim40, wherein the width of the throat is less than about 80% of theseating surface.